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A260008
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Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000101 00010101 or 01010101.
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1
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36, 49, 109, 209, 436, 828, 1744, 3344, 7005, 13424, 28067, 53992, 112602, 216997, 451535, 872258, 1811173, 3505729, 7264641, 14089470, 29141208, 56621872, 116900698, 227536583, 468975418, 914316503, 1881490568, 3673849908
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-2) + 7*a(n-4) + a(n-5) + 2*a(n-6) + a(n-7) - a(n-8) + a(n-9) for n>10.
Empirical g.f.: x*(36 + 49*x + 37*x^2 + 111*x^3 - 34*x^4 + 31*x^5 - 12*x^6 - 18*x^7 + 25*x^8 - 10*x^9) / (1 - 2*x^2 - 7*x^4 - x^5 - 2*x^6 - x^7 + x^8 - x^9). - Colin Barker, Dec 27 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..1....0..1..0....0..0..1....0..0..0....0..0..0....0..0..0....1..0..1
..0..1..0....1..0..1....0..1..0....0..0..1....0..0..0....0..0..1....0..1..0
..1..0..1....0..1..0....1..0..1....0..1..0....1..0..1....0..1..0....1..0..1
..0..1..0....0..0..1....0..1..0....0..0..1....0..1..0....0..0..1....0..0..0
..1..0..1....0..0..0....0..0..1....0..0..0....1..0..1....0..1..0....0..0..1
..0..0..0....1..0..1....0..1..0....0..0..1....0..0..0....1..0..1....0..1..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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